Research Article - Journal of Gastroenterology and Digestive Diseases (2018) Volume 3, Issue 1

Mirtazapine in diarrhea-predominant irritable bowel syndrome: an open label study.

Background and objective: Antidepressant drugs including tricyclic antidepressants and selective serotonin reuptake inhibitors are established for use in the management of irritable bowel syndrome, but their efficacy over placebo remains modest. Mirtazapine is a novel antidepressant with multimodal mechanism of action. We aimed to study its efficacy in diarrhea-predominant irritable bowel syndrome (IBS-D). Methods: Sequential IBS-D patients were administered oral mirtazapine for 12 weeks. Dosage commenced at 15 mg daily, increasing to 30 mg if tolerated. Outcomes included change in IBS symptom severity score, Hospital anxiety and depression scale and diary-derived symptom scores (diarrhea, pain, urgency) post-treatment compared with baseline. Results: 16 patients (13 female, mean age 39) were included. Eleven patients received 15 mg while five received 30 mg mirtazapine. 11 patients (69%) were deemed responders, classified as those in whom IBS symptom severity score reduced by >50 points post-treatment. Significant reductions from pre- to post-therapy in mean hospital anxiety (difference -2.0, P=0.04) and depression (difference - 0.7, P=0.04) scales were noted. The mean IBS symptom severity score also reduced severity with therapy, from 313 to 215 (P<0.01). Significant reduction in symptom scores for abdominal pain, urgency, diarrhea and bloating were noted (all P ≤ 0.01). No serious adverse events occurred, but minor adverse effects were noted in 9 subjects. Conclusions: In this open-label study, mirtazapine demonstrated efficacy in improving both gastrointestinal and psychological symptoms in IBS-D. Its potential utility should be further evaluated in larger controlled trials.

Author(s): Sanagapalli S*, Kim E1, Zarate-Lopez N, Emmanuel A

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